The invention relates to apparatus for performing mechanical tests on structures, and in particular on energy absorber elements in the field of railways. Such tests have the particularity of requiring energy levels that can be relatively high, and of the order of 6 megajoules (MJ).
In the field of railways, impact testing apparatus is known in which a vehicle is put in motion on a rail track by means of a locomotive or else by gravity, using a track segment on a gradient. Once in motion, the vehicle hits an obstacle disposed on the rail track. Unfortunately, such testing apparatus suffers from the drawback of requiring a run up distance that is long, and generally longer than 500 meters (m), when the vehicle is xe2x80x9claunchedxe2x80x9d by a locomotive, or else a difference in level that is considerable when gravity is used to put it in motion, which makes the facilities dedicated to such testing very costly.
Document FR 2 765 685 discloses acceleration and deceleration apparatus using a pyrotechnics launcher. Such a pyrotechnics launcher offers the advantage of being capable of propelling moving equipment on a test track with programmed acceleration and with high energy. However, the testing apparatus disclosed in that document is unsuitable for launching a variety of different types of vehicle (in particular different types of rail vehicle), and does not make it possible to perform a wide variety of mechanical tests involving a variety of quantities of energy.
In the field of railways, it is necessary to test different types of energy absorber having widely different absorption capacities. The most recent rail vehicles are equipped with energy absorber elements disposed in alignment with the underframe of the vehicle and dimensioned to absorb large quantities of energy, e.g. to damp an impact with another rail vehicle, but they can also be provided with energy absorber elements dimensioned to deform as from lower energy levels, and often associated with the structure of the driver""s cab, making it possible to absorb an impact involving less energy, such as an impact with a road truck.
Thus, an object of the present invention is to provide apparatus for performing mechanical tests on structures, and in particular on energy absorbers in the field of railways, which apparatus includes a pyrotechnics launcher that makes it possible to launch moving elements of widely differing sizes under high energy while also minimizing the risk of the moving elements pitching. Another object of the invention is to provide apparatus for performing impact tests that is very adaptable by making it possible to test absorber elements of widely differing ratings and strengths.
To this end, the invention provides apparatus for performing mechanical tests on structures, in particular on energy absorber elements in the field of railways, wherein a pyrotechnics launcher comprising a launch tube slidably receiving a thrust rod is disposed at one end of a segment of rail track, said pyrotechnics launcher being supported in its central portion by a support element and being prevented from moving backwards by a buffer stop element disposed behind the pyrotechnics launcher, said support element and said buffer stop element including fixing means making it possible to hold said pyrotechnics launcher at various heights relative to the rails of the rail track.
In particular embodiments, the apparatus of the invention for performing mechanical tests may have one or more of the following characteristics taken in isolation or in any technically feasible combination:
the buffer stop element and the support element stand on a concrete slab, said concrete slab also supporting a portion of the segment of rail track;
the concrete slab is anchored in the ground by means of anchoring piles driven into the ground and embedded in part in said concrete slab;
the concrete slab is provided with a pit extending between the rails of the rail track, said pit receiving a launch trolley which is mounted to slide between the rails and which can be propelled by the thrust rod;
the fixing means for fixing the pyrotechnics launcher to the support element and to the buffer stop element make it possible to lower the pyrotechnics launcher below the level of the rails of the rail track, and the pit has a wall facing towards the pyrotechnics launcher and that can receive an energy absorber element which is to be tested and against which said launch trolley crashes;
the support element is a gantry frame comprising two vertical elements provided with multiple holes making it possible to fix brackets at various heights for supporting a ring surrounding the launch tube, it being possible for the ring to pivot on the brackets about a horizontal axis perpendicular to the axis of the launch tube;
the buffer stop element is constituted by a block of concrete having a substantially vertical wall against which a fixing plate is fixed that is disposed accurately perpendicular to the plane of the rails of the rail track, said fixing plate being provided with multiple holes making it possible to fix, at various heights, an abutment bracket to the end of which the rear end of the pyrotechnics launcher is fixed; and
the thrust rod is supported directly by a vehicle by means of interface apparatus provided with means for adjusting the alignment of the thrust rod on the axis of the launch tube.